Catheters have been in common use in medical practice for many years. They are used to probe locations inside a body lumen which are otherwise unreachable without surgery. A catheter is first inserted into a major vein or artery, or other body lumen which is near the body surface. The catheter is then guided to the area of concern by further inserting it into the body lumen. As medical knowledge increases, catheterizations have become more complicated and more exacting. In many situations the ability to control the exact position and orientation of the catheter tip largely determines how useful the catheter is.
The body of a catheter is long and tubular. The problem of control over such a device has resulted in catheters which are generally rigid and preformed into specific shapes. This is exemplified by U.S. Pat. No. 3,485,234 to Stevens, which describes a method for making a catheter in any desired shape. However, given the complexity of body lumens, each preformed catheter can only reach certain areas. Thus, for many examinations, multiple catheters are needed, either inserted together or each one in turn. In either case, this greatly adds to the complexity of the procedure and creates additional risk for the patient.
Flexible catheters having steerable tips are also known. Such catheters have control handles at their proximal ends controlling the tips. U. S. Pat. No. 4,586,923 to Gould describes many of these. The mechanisms described involve control handles which are asymmetrical. This results in the control handle being less effective when it is rotated, as the controls are no longer in a convenient position to use. Control of the catheter is therefore limited, as the user is not free to rotate the device without losing some control over it.
Such steerable catheters include a stainless steel puller wire which extends from the control handle to the catheter tip. A problem with such puller wires is that when the catheter is bent, the puller wire tends to retain the bend, and resist straightening.
A catheter often has probes of some kind, e.g., electrodes, on its tip in order to deliver stimuli and/or take measurements within the body lumen. In such a catheter, the probe is electrically connected to an instrument capable of generating the stimuli or recording and/or interpreting signals received by the probes. The connection to this additional instrument generally involves the use of multiple wires which plug into separate sockets, as shown in U.S. Pat. No. 4,603,705 to Speicher, or the use of a single multiple pin plug which fits into a corresponding multiple pin socket. In either case, if the catheter is rotated, the connections must be unplugged and reset, since they otherwise restrict the movement of the catheter. This problem further increases the risks mentioned above in regards to multiple catheters. Each catheter has its own connections, all of which will need to be reset as the catheters are manipulated. The additional loss of data flow and increased procedure length further increase the risk to the patient.